(1) Field of the Invention
This invention relates to a carbide hobbing machine for hobbing steel-made gears. More particularly, the invention relates to an improvement in the driving system in such carbide hobbing machine.
(2) Description of the Prior Art
If steel-made gears can be hobbed at high speeds with a powerful single cutting by using a carbide hob, the efficiency of manufacturing gears will be remarkably increased and it will lead to great economical advantages. Therefore, various makers in the world have eagerly attempted to develop carbide hobbing machines and since around 1969, carbide hobbing machines have been exhibited in international trade fairs held in Europe. In these carbide hobbing machines, a play is provided in a driving system or a hydraulic bearing is adopted for a hob shaft so as to enable a high speed rotation of the hob shaft. In some machines, special means are adopted for preventing thermal deformation. However, these modifications are not essential improvements and these conventional carbide hobbing machines do not substantially rise above customary high speed hobbing machines. Accordingly, when a cutting edge of the carbide hob starts an operation of hobbing a work piece for a gear, a large shock is imposed on the cutting edge, and even during the hobbing operation, the cutting edge undergoes violent vibrations. Therefore, chipping is readily caused during the operation. Because of these defects, development of carbide hobbing machines only makes very slow progress.